The vasorelaxant effect of gallic acid involves endothelium-dependent and -independent mechanisms

Abstract

The mechanisms of action involved in the vasorelaxant effect of gallic acid (GA) were examined in the isolated rat thoracic aorta. GA exerted a relaxant effect in the highest concentrations (0.4-10mM) in both endothelium-intact and endothelium-denuded aortic rings. Pre-incubation with L-NAME, ODQ, calmidazolium, TEA, 4-aminopyridine, and barium chloride significantly reduced the pEC50 values. Moreover, this effect was not modified by indomethacin, wortmannin, PP2, glibenclamide, or paxillin. Pre-incubation of GA (1, 3, and 10mM) in a Ca(2+)-free Krebs solution attenuated CaCl2-induced contractions and blocked BAY K8644-induced vascular contractions, but it did not inhibit a contraction induced by the release of Ca(2+) from the sarcoplasmatic reticulum stores. In addition, a Western blot analysis showed that GA induces phosphorylation of eNOS in rat thoracic aorta. These results suggest that GA induces relaxation in rat aortic rings through an endothelium-dependent pathway, resulting in eNOS phosphorylation and opening potassium channels. Additionally, the relaxant effect by an endothelium-independent pathway involves the blockade of the Ca(2+) influx via L-type Ca(2+) channels.

Polyphenolic compounds of Euphorbia umbellata (Pax) Bruyns (Euphorbiaceae) improved endothelial dysfunction through arginase inhibition

“…Quercetin also improved NOS3 expression in the mesenteric vessels (114%, Figure 6), although a significant difference was not observed (p = .062), demonstrating that small resistance vessels (mesenteric vascular bed), as well as conductance arteries (aorta), can also be appropriate tissues to access the effects of quercetin on NOS expression/activities (Duarte et al, 2002;Shen et al, 2012). Oliveira et al, 2016;Shen et al, 2012). These actions also contribute to the total vasoactive effects of these polyphenolic compounds as part of their endothelium-dependent mechanisms.…”

Acute and Sub-Acute Antihypertensive Effects of Syzygium polyanthum Leaf Extracts with Determination of Gallic Acid using HPLC Analysis

“…Thus, an inhibition of renin is suggested to suppress the production of angiotensin II, which in turn results in reduction of blood pressure. Few in vitro studies have further demonstrated the vasorelaxation effect by gallic acid 14,15 which was mediated through nitric oxide/cGMP signaling pathway. Gallic acid may act as a potassium channel opener and also as a calcium channel blocker to cause vasorelaxation.…”

“…Gallic acid may act as a potassium channel opener and also as a calcium channel blocker to cause vasorelaxation. 15 The resultant vasorelaxation effect may reduce the total peripheral resistance resulting in reduction of blood pressure. Interestingly, our recent study has shown that the aqueous and methanolic extract of S. polyanthum leaves extract have some vasorelaxation properties when tested on isolated thoracic aorta rings of WKY and SHR rats.…”

“…Among the identified compounds, gallic acid were previously shown to have some potentials with respect to antihypertensive action. Oral gallic acid was found to significantly reduce blood pressure of diabetic rats 12 and to exhibit renin-inhibitory 13 and vasorelaxation 14,15 effects. However, none has identified the phytochemicals in aqueous decoction of this plant leaf as traditionally prepared.…”

Antihypertensive activity and vascular reactivity mechanisms of Vitex pubescens leaf extracts in spontaneously hypertensive rats

“…Inhibitions of Ca 2+ influx through voltage-dependent calcium channels (VDCC) by the most active fraction of V. pubescens were assessed as described by Oliveira et al. [ 22 ]. Denuded aortic rings were equilibrated for 30 min in normal KPS.…”